Traditionally, signaling devices within elevator systems, such as hall call push buttons, hall lanterns, and positions indicators, which required separate wiring. For example, a twenty floor building would require a signal conductor for each UP and DOWN elevator call button for each floor, where nineteen of the twenty floors would have both UP and DOWN call buttons. Therefore, thirty eight signal conductors would be needed for these nineteen floors. The ground floor and top floor (floor twenty) would respectively have an UP and DOWN call button, which would each require a signal conductor. This brings the total number of signal conductors for the hall call buttons alone to forty. A common conductor (ground conductor) would also be required. If the UP and DOWN arrows were fitted with call acknowledgement lamps, an additional forty conductors would also be required (i.e., for the twenty floor example). Hall lanterns for each floor (for example, up and down arrows located above the hall entrance) would also require two conductors and a ground conductor. Hence, traditional elevator system wiring installations were both more labor intensive and more complex in terms of the higher volume of conductors needed in the wiring schemes. Maintenance and fault finding in these traditional wiring approaches are also more challenging in comparison to more simplified wiring installations.
Elevator systems using microprocessor based equipment provide a reduction in installation wiring time and the number of wires used in the installation. However, these systems use serial communications over data busses, and therefore, still require discrete wiring installation, which is relatively labor intensive.
Some elevator system manufacturers have adapted power line carrier (PLC) technology to provide signal communications between the system controller, car controllers, and various hall fixtures (e.g., hall call button). Using the PLC format for communications, signaling data is transmitted over the building AC power lines. Although PLC reduces the installation costs, it uses the existing electrical power lines within a building as a communications medium. Therefore, equipment using PLC communication are subjected to changes in impedance and power line noise which occur as a result of load changes from different electrical appliances drawing power from various AC sockets within the building. Furthermore, PLC communications is subjected to restrictions and regulations (in US, by the FCC) that are imposed on modulation frequencies, conducted and radiated emissions, and interfacing safety between the power line and communication equipment accessing the power line transmission medium. Finally, transmission of signals over the AC wiring of a building does raise a security risk, where signal tampering and hacking is aided through the use of readily available wall sockets.
Therefore, it is an object of the present invention to provide a simplified wiring system for elevators, wherein the existing elevator wiring infrastructure is used for signal transmission.
It another object of the present invention to use existing elevator wiring for transmitting information over a secure transmission medium.
It is yet another object of the present invention to provide a flexible transmission system capable of using less complex transmission schemes.
It is another object of the present invention to derive electrical power for the existing elevator wiring for providing electrical power to various components of the transmission system.